/S>-t. ^. ^t-it.t.A^xje. ^ U.S. a- . 



Dendroeca auduboni (^Tovjns.) ^^zVo'.— Breeding rather abundantly 

 in the Big Horn Mountains but only one nest was found. Several descrip- 

 tions of the eggs of the Western Yellow-rump have recently appeared, 

 and its breeding habits are now fairly well known. My nest was found 

 on the 17th of June in a young pine tree growing on the top of a ridge at 

 the edge of a deep canon, at an elevation of 6,500 feet. It was about seven 

 feet from the ground and placed against the main trunk, supported by and 

 partly saddled upon two twigs. It is large for the size of the bird, 

 measuring 4X4 inches: internally i^Xi|. Externally it is composed 

 of many small twigs and fine strips of bark; within this is a thick wall 

 of well matted strips of a weed and of bark and pine needles. The inner 

 lining consists of fine fibrous roots and hairs, with a feather or two. 

 The most curious feature of the nest is a circle of feathers of Richardson's 

 Grouse attached to the rim for nearly the entire circumference, a small 

 bare space being left which was apparently used by the bird on entering. 

 These feathers are fastened to the rim by the larger ends and are directed 

 upwards and inwards forming a sort of canopy which completely hid the 

 female while sitting. The appearance is very peculiar and quite unlike 

 anything I have seen, for this use of the feathers is evidently intentional 

 and is very different from what is seen in nests with a lining of loose 

 feathers in which the bird sinks nearly out of sight. One egg was broken ; 

 the other four, far advanced in incubation, average .68X.S3. The ground 

 color is a decidedly greenish-white, sparingly marked over the entire 

 surface with small spots and dots of black, brown, and lavender, the latter 

 predominating, and form an irregular wreath around the larger end. 



Bua N.O.O, O.Oot, 1881, p. Z O 6". 



Birds at Twio Lakes, Col. W.D.ScoU 



12. Dendroeca auduboni. Audobon'.S Warbi.er. — Not very com- 

 mon. Two females, taken the 15th of June, showed signs of incubating, 

 and the plumage was much worn. On the 25th of June I took a nest con- 

 taining four eggs nearly ready to hatch. The nest is a rather bulky struc- 

 ture, composed of twigs of sage-brush and fine grass, and is lined with soft 

 hair and large feathers. In general shape it is flat and rather sliallow, as 

 the following dhnensions show : Diameter outside, four inches ; diameter 

 inside, three inches ; depth, two and a half inches outside and two inches 

 inside. It was situated on the outer twigs of a large pine-tree, five feet 

 from the ground. It contains four eggs, of a light greenish tint, with a 

 circle of dark brown spots at the larger end. They are quite sharply 

 pointed, and of the following dimensions : .76 x .55, .72 x .58. I give the 

 dimensions of only two, as the others were too badly broken to yield accu- 

 rate measurements. The nest was not fastened in any crotch, but simply 

 laid on a bunch of pine leaves, and was sheltered by another bunch di- 

 rectly above it. On the 29th of June I found a second nest containing 

 four young a day or two old. This one was situated in the topmost 

 branches of a small fir-tree, about twenty-five feet from the ground. The 

 nest is essentially the same in structure as the one above described. Ou 

 July 9 I took young which had just left the nest. • 



Bull N.O.O. 4, April, 187©, p. 03 



